<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE html
    PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
  <title>Qt 4.3: mandelbrotwidget.cpp Example File (threads/mandelbrot/mandelbrotwidget.cpp)</title>
  <link href="classic.css" rel="stylesheet" type="text/css" />
</head>
<body>
<table border="0" cellpadding="0" cellspacing="0" width="100%">
<tr>
<td align="left" valign="top" width="32"><a href="http://www.trolltech.com/products/qt"><img src="images/qt-logo.png" align="left" width="32" height="32" border="0" /></a></td>
<td width="1">&nbsp;&nbsp;</td><td class="postheader" valign="center"><a href="index.html"><font color="#004faf">Home</font></a>&nbsp;&middot; <a href="classes.html"><font color="#004faf">All&nbsp;Classes</font></a>&nbsp;&middot; <a href="mainclasses.html"><font color="#004faf">Main&nbsp;Classes</font></a>&nbsp;&middot; <a href="groups.html"><font color="#004faf">Grouped&nbsp;Classes</font></a>&nbsp;&middot; <a href="modules.html"><font color="#004faf">Modules</font></a>&nbsp;&middot; <a href="functions.html"><font color="#004faf">Functions</font></a></td>
<td align="right" valign="top" width="230"><a href="http://www.trolltech.com"><img src="images/trolltech-logo.png" align="right" width="203" height="32" border="0" /></a></td></tr></table><h1 align="center">mandelbrotwidget.cpp Example File<br /><sup><sup>threads/mandelbrot/mandelbrotwidget.cpp</sup></sup></h1>
<pre><span class="comment"> /****************************************************************************
 **
 ** Copyright (C) 2004-2008 Trolltech ASA. All rights reserved.
 **
 ** This file is part of the documentation of the Qt Toolkit.
 **
 ** This file may be used under the terms of the GNU General Public
** License versions 2.0 or 3.0 as published by the Free Software
** Foundation and appearing in the files LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file.  Alternatively you may (at
** your option) use any later version of the GNU General Public
** License if such license has been publicly approved by Trolltech ASA
** (or its successors, if any) and the KDE Free Qt Foundation. 
**
** Please review the following information to ensure GNU General
** Public Licensing requirements will be met:
** http://trolltech.com/products/qt/licenses/licensing/opensource/. If
** you are unsure which license is appropriate for your use, please
** review the following information:
** http://trolltech.com/products/qt/licenses/licensing/licensingoverview
** or contact the sales department at sales@trolltech.com.
**
** In addition, as a special exception, Trolltech, as the sole
** copyright holder for Qt Designer, grants users of the Qt/Eclipse
** Integration plug-in the right for the Qt/Eclipse Integration to
** link to functionality provided by Qt Designer and its related
** libraries.
**
** This file is provided "AS IS" with NO WARRANTY OF ANY KIND,
** INCLUDING THE WARRANTIES OF DESIGN, MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE. Trolltech reserves all rights not expressly
** granted herein.
 **
 ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 **
 ****************************************************************************/</span>

 #include &lt;QtGui&gt;

 #include &lt;math.h&gt;

 #include &quot;mandelbrotwidget.h&quot;

 const double DefaultCenterX = -0.637011f;
 const double DefaultCenterY = -0.0395159f;
 const double DefaultScale = 0.00403897f;

 const double ZoomInFactor = 0.8f;
 const double ZoomOutFactor = 1 / ZoomInFactor;
 const int ScrollStep = 20;

 MandelbrotWidget::MandelbrotWidget(QWidget *parent)
     : QWidget(parent)
 {
     centerX = DefaultCenterX;
     centerY = DefaultCenterY;
     pixmapScale = DefaultScale;
     curScale = DefaultScale;

     qRegisterMetaType&lt;QImage&gt;(&quot;QImage&quot;);
     connect(&amp;thread, SIGNAL(renderedImage(const QImage &amp;, double)),
             this, SLOT(updatePixmap(const QImage &amp;, double)));

     setWindowTitle(tr(&quot;Mandelbrot&quot;));
     setCursor(Qt::CrossCursor);
     resize(550, 400);
 }

 void MandelbrotWidget::paintEvent(QPaintEvent * <span class="comment">/* event */</span>)
 {
     QPainter painter(this);
     painter.fillRect(rect(), Qt::black);

     if (pixmap.isNull()) {
         painter.setPen(Qt::white);
         painter.drawText(rect(), Qt::AlignCenter,
                          tr(&quot;Rendering initial image, please wait...&quot;));
         return;
     }

     if (curScale == pixmapScale) {
         painter.drawPixmap(pixmapOffset, pixmap);
     } else {
         double scaleFactor = pixmapScale / curScale;
         int newWidth = int(pixmap.width() * scaleFactor);
         int newHeight = int(pixmap.height() * scaleFactor);
         int newX = pixmapOffset.x() + (pixmap.width() - newWidth) / 2;
         int newY = pixmapOffset.y() + (pixmap.height() - newHeight) / 2;

         painter.save();
         painter.translate(newX, newY);
         painter.scale(scaleFactor, scaleFactor);
         QRectF exposed = painter.matrix().inverted().mapRect(rect()).adjusted(-1, -1, 1, 1);
         painter.drawPixmap(exposed, pixmap, exposed);
         painter.restore();
     }

     QString text = tr(&quot;Use mouse wheel or the '+' and '-' keys to zoom. &quot;
                       &quot;Press and hold left mouse button to scroll.&quot;);
     QFontMetrics metrics = painter.fontMetrics();
     int textWidth = metrics.width(text);

     painter.setPen(Qt::NoPen);
     painter.setBrush(QColor(0, 0, 0, 127));
     painter.drawRect((width() - textWidth) / 2 - 5, 0, textWidth + 10,
                      metrics.lineSpacing() + 5);
     painter.setPen(Qt::white);
     painter.drawText((width() - textWidth) / 2,
                      metrics.leading() + metrics.ascent(), text);
 }

 void MandelbrotWidget::resizeEvent(QResizeEvent * <span class="comment">/* event */</span>)
 {
     thread.render(centerX, centerY, curScale, size());
 }

 void MandelbrotWidget::keyPressEvent(QKeyEvent *event)
 {
     switch (event-&gt;key()) {
     case Qt::Key_Plus:
         zoom(ZoomInFactor);
         break;
     case Qt::Key_Minus:
         zoom(ZoomOutFactor);
         break;
     case Qt::Key_Left:
         scroll(-ScrollStep, 0);
         break;
     case Qt::Key_Right:
         scroll(+ScrollStep, 0);
         break;
     case Qt::Key_Down:
         scroll(0, -ScrollStep);
         break;
     case Qt::Key_Up:
         scroll(0, +ScrollStep);
         break;
     default:
         QWidget::keyPressEvent(event);
     }
 }

 void MandelbrotWidget::wheelEvent(QWheelEvent *event)
 {
     int numDegrees = event-&gt;delta() / 8;
     double numSteps = numDegrees / 15.0f;
     zoom(pow(ZoomInFactor, numSteps));
 }

 void MandelbrotWidget::mousePressEvent(QMouseEvent *event)
 {
     if (event-&gt;button() == Qt::LeftButton)
         lastDragPos = event-&gt;pos();
 }

 void MandelbrotWidget::mouseMoveEvent(QMouseEvent *event)
 {
     if (event-&gt;buttons() &amp; Qt::LeftButton) {
         pixmapOffset += event-&gt;pos() - lastDragPos;
         lastDragPos = event-&gt;pos();
         update();
     }
 }

 void MandelbrotWidget::mouseReleaseEvent(QMouseEvent *event)
 {
     if (event-&gt;button() == Qt::LeftButton) {
         pixmapOffset += event-&gt;pos() - lastDragPos;
         lastDragPos = QPoint();

         int deltaX = (width() - pixmap.width()) / 2 - pixmapOffset.x();
         int deltaY = (height() - pixmap.height()) / 2 - pixmapOffset.y();
         scroll(deltaX, deltaY);
     }
 }

 void MandelbrotWidget::updatePixmap(const QImage &amp;image, double scaleFactor)
 {
     if (!lastDragPos.isNull())
         return;

     pixmap = QPixmap::fromImage(image);
     pixmapOffset = QPoint();
     lastDragPos = QPoint();
     pixmapScale = scaleFactor;
     update();
 }

 void MandelbrotWidget::zoom(double zoomFactor)
 {
     curScale *= zoomFactor;
     update();
     thread.render(centerX, centerY, curScale, size());
 }

 void MandelbrotWidget::scroll(int deltaX, int deltaY)
 {
     centerX += deltaX * curScale;
     centerY += deltaY * curScale;
     update();
     thread.render(centerX, centerY, curScale, size());
 }</pre>
<p /><address><hr /><div align="center">
<table width="100%" cellspacing="0" border="0"><tr class="address">
<td width="30%">Copyright &copy; 2008 <a href="trolltech.html">Trolltech</a></td>
<td width="40%" align="center"><a href="trademarks.html">Trademarks</a></td>
<td width="30%" align="right"><div align="right">Qt 4.3.5</div></td>
</tr></table></div></address></body>
</html>
